One familiar technique they use is to attribute to global warming almost any unusual weather event anywhere in the world. Last week, for instance, it was reported that Russia has recently been experiencing its hottest temperatures and longest drought for 130 years. The head of the Russian branch of WWF, the environmental pressure group, was inevitably quick to cite this as evidence of climate change, claiming that in future “such climate abnormalities will only become more frequent”. He didn’t explain what might have caused the similar hot weather 130 years ago.

Meanwhile, notably little attention has been paid to the disastrous chill which has been sweeping South America thanks to an inrush of air from the Antarctic, killing hundreds in the continent’s coldest winter for years.

In America, the National Oceanic and Atmospheric Administration (NOAA) has been trumpeting that, according to its much-quoted worldwide temperature data, the first six months of this year were the hottest ever recorded. But expert analysis on Watts Up With That, the US science blog, shows that NOAA’s claimed warming appears to be strangely concentrated in those parts of the world where it has fewest weather stations. In Greenland, for instance, two of the hottest spots, showing a startling five-degree rise in temperatures, have no weather stations at all.